Machine tools, such as numerically controlled lathes, are utilized to produce many parts that are basically round in shape and often short in length. One of the limitations in the productivity of such machines is the ability to load and unload the workpieces.
In one type of mechanism heretofore used, mechanical clamping arms are pivotally mounted and movable toward and away from the workpiece to grip and release the workpiece. A problem with such mechanisms is that if the diameter of the workpiece changes, the position of the centerline of the workpiece changes.
Accordingly, the present invention is directed to a loading and unloading system that obviates this problem; which can be utilized to handle a variety of sizes of parts; which can handle parts to be held either on the outside diameter or in the bore.
In accordance with the invention, a loader-unloader system is provided for loading and unloading workpieces in a machine tool wherein each workpiece is held in position about an axis during which various machine operations may be performed on the tool. The system comprises a loading chute or conveyor adapted to deliver articles in succession to a loading position and an unloading chute adapted to receive workpieces. A loader-unloader assembly is provided adjacent to the chutes and comprises carriage rails extending along an axis parallel to the longitudinal axis of the machine, a carriage movable along the rails, and means for moving the carrier back and forth along the rails. A loader-unloader head assembly is mounted on the carrier and includes a head for gripping a workpiece and is pivotally mounted on the carriage for swinging movement into and out of position adjacent the machine tool and for reciprocating movement toward and away from the axis of the machine tool. The assembly includes a multiplicity of fingers on the head that are movable in a substantially linear path toward and away from one another to grip and release a workpiece.
A second set of fingers may be mounted on the head to permit simultaneous loading and unloading.